Semiautomatic telephone system



June 11, 1929.

w. o. PASSMORE 1,716,563

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SEMIAUTOMATIC TELEPHONE SYSTEM Original Filed Now 25, 1924 6 Sheds-Sheet 3 01" 5 Passmura June 11, 1929; w, o, PASSMORE I 1,716,563

SEMIAUTOMATIC TELEPHONE SYSTEM Original Filed Nov. 25, 1924 e Sheets-Sheet 4 Inuen1ur Q Mflham Ugl kn; Fassmur'e Q HUT-.1:

June 11, 1929. w. o. PASSMORE SEMIAUTOMATIC TELEPHONE SYSTEM Original Fild Nov, 25, 1924 6 She ts-Sheet Imren n1" Lillham Uglesby Fassmnrs HIT- Jun 11, 1929. w, 0, PASSMQ'RE 1,716,563

SEMIAUTOMATIC TELEPHONE-SYSTEM 'Ori Filed Nov. 25 1924 6 Sheets-Sheet 6 v Inueulur I Patented June 11, 1929.

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WILLIAM OGLESBY PASSM'ORE, OF LIVER-POOL, ENGLAND, ASSIGNOR, BY MESNE S- SIGNIi'IE-NTS, 'lO AUTOMATIC ELECTRIC INC, OF CHICAGO, ILLINOIS, A. CORPORA- TION OF D'ELA'WARE.

SEMIAUTOMATIG TELEPHONE SYSTEM.

Application filed November 25, 1824, Serial No. 752,138, and. in Great Britain November 30, 1923. Renewed November 6, 1928.

The present invention relates to semi-automatic telephone systems and more particularly to systems in which calls may have to be completed either to automatic or manual subscribers. The invention will be described in detail in connection with an arrangementwh-ereby calls are set up from a manual exchange but it should be understood that many of the features of the invention are applicable to cases in which automatic subscribers originate calls which are then completed by means of register translators.

Calls which are extended over automatic numerical switches to manual exchanges will generally be dealt with at call indicator positions where the wanted number is displayed to the operator by means of lamps or other indicators. It has already been proposed, as described in the co-pending application, of Ostline, Serial No. 630.1 26, filed April 9. 1923, issued Aug. 1%, 1928 as Patent 1,680,565, to transmit the wanted number over the trunk line not by means of impulses such as are used for operating stepping switches but in a special code whereby the transmission time may be appreciably reduced.

It is one object of the present invention to provide an impulse sender which will send ordinary impulses to operate the switches for selecting the exchange and then according an automatic or a manual. exchange has been selected will transmit the numerical portion of the wanted number in ordinary imp ilses or in a special code for operating a call indicator. Ordinary impulses or circuit interruptions such as are used for operating stcp-by-stcp switches will. for the sake of convenience be termed hereafter stepping impulses. The arrangement whereby the trunk lines outgoing from an operators position lead to automatic switches having access to both manual and automatic exchanges presents the advantage that the code sending device and the storage devices for recording the wanteo subscribers number may be provided in groiu'is common to all or to a large number of the call indicator exchanges in a network.

According to one feature of the invention an impulse sender is provided comprising register sets on which wanted subscribers numbers are stored and sending devices or two different kinds associated with the register sets, one for sending impulses to operate the switches which periorm an exchange selecting function and the other for sending impulses in a code suitable for operating call indicators at the exchange selected.

According to another feature of the invention in an impulse sender comprising register sets and two different kinds of sending devices, means are provided whereby one sending device transmits impulses of one kind corresponding to a portion of the required number and be other sending device subsequently transmits impulses of a different kind corresponding to another portion of the required number. Determining means are also provided whereby either one sending device or the other is brought into operation depending upon the destination of the call.

A further feature of the invention is the provision of an impulse sender comprising a register set on which wanted subscribersnumbers are adapted to be set up and sending devices of two kinds controlled by the register set, that part of the register set which registers the exchange designation of the wanted subscriber being adapted to cause the operation of one sending device to control switches for selecting the required exchange and also to determine whether subsequently the first device will continue to operate or the second device be brought into operation to transmit impulses ot a different kind in accordance with the setting of the other part of the register set which registers the numerical designation of the wanted subscriber.

Still another feature is that where connections are setup over automatic switches with the help of operators by means of keyboard controlled impulse senders common to a large group of? operators, the same impulse senders may be used for setting up connections to both automatic and manual exchanges.

Other features relatev to the delaying of the sending of code impulses until the call in dicator operator is ready to receive them. to the use of trunk finders for connecting an outgoing trunk with an impulse sending device to a device for compensating the code sending circuit for different lengths of trunk line and to various advantageous smaller provisions forimproving the operation of the impulse sender and facilitating the establishment of calls.

These "features will be better understood from the following detailed description of the operation of one embodiment of the invention, though, as mentioned above, it may be applied in other circumstances than those shown and obviously detail modifications may be made without exceeding the scope of the invention.

In the accompanying drawings, Fig. 1 shows the general layout of the. system described, and Fig. 2 shows a trunk finder and the apparatus associated with an outgoing trunk line. Fig. 3 shows the operators key set, the outlet finoer and a sender selector, Fig. 4, indicates the input control switch and the sender controlling relays, while Fig. 5 shows the storage relays, code switch and intermediate distributing frame. Fig. 6 illustrates the output control switch, and two different sender switches and the compensating arrangements. Itwill be understood that Figs. 2-6 are to be placed together with the corre sponding lines in alignment in order to form the complete system as diagrammatically shown in Fig. 1.

The general layout of the system, Fig. 1, in many respects closely resembles that shown in the co-pending application of Gillings, Serial No. 723,124, filed June 30, 1924, but dil'lers in several important points, this layout will first be briefly described. The operator, at the position O at the originating manual exchange will be signalled in the usual manner by a calling subscriber and on learning his requirements, will repeat the wanted subscribers number to the tandem operator o"er an order wire (not thown). The tandem operator will thereupon give her the number of an idle intereXchange junction line, at the same time pressing the assignment key A associated with this line. In the drawing, Fig. 1, only one such junction line is shown.

In response to the pressure of the assignment key, a circuit is completed over the outlet finder OF, and back contact and armature G in the preselected outlet for the sender selector SS which thereupon commences hunting for a free sender. At the same time the trunk finder TF associated with this outlet is started up to find the line in connection with which the assignment key has been pressed. When these switches find an idle sender and the assigned trunk line respectively, the operator is notified by the lighting of a lamp and she may then set up the required number by operating the appropriate lreys of her key set K.

In response to the operation of the first key, a circuit is completed over the outlet finder OF in the position shown, back contact and armature G sender selector SS armature N and itsback contact, over the wipers oi the input control switch IOS in first position to the first set of storage relays'all of which are represented in Fig. 1 by the rectangle SE. The switch IOS is moved on one step as each key is released, and in consequence a different set of storage relays is operated each time a key is pressed. When three digits have been registered, a circuit is completed for starting up the code switch OS which then hunts to find contacts whichhave been marked by the operation of the first three sets of storage relays. In the meantime the operator will be setting up the remainder of the number which in the case described will comprise four numerical digits.

It will be assumed in the present instance, that the call is going to a call indicator exchan e, and hence the exchange selecting digits, after being translated as will be more fully described subsequently, are transmitted in the form of impulses for operating stepby-step switches of the ordinary type, while the four digits corresponding to the actual subscribefis number are subsequently sent out over the trunk line in code whereby a considerable saving of transmission time may be efiected.

When all the digits have been set up and assuming that the A operator at the originating manual exchange has already plugged in, the sending of stepping impulses will commence under the control of the code switch OS. These impulses traverse a path from the stepping impulse sender SIS, back contact and armature P output control switch OOS, front contact and armature sender selector SS armature G and its front contact, trunk finder TF front contact and armature F to selectors such as D and E; The translation of the digits originally stored on the first three storage relay groups is effected by suitable cross connections at the intermediate distributing trame IDF. hen all the exchange selecting digits, in this case 2, have been sent out, armature P is operated and the code sender OIS comes into operation. This is then controlled from the storage relays SR so as to send out over the trunk line code impulses which are received at a call indicator exchange and decoded, and by suitable means displayed to the operator.

When the sending of impulses is finished, the impulse sender is released and may be again taken into use for a further call, while the release of the armature F completes the speaking connection. As will appear subsequently, the outlet finder OF is moved on one step as soon as the sendingot impulses commences, and the operator may then at once commence setting up another connection over an idle impulse sender seized for instance by the sender selector SS? associated with the second outlet.

The general principles underlying the invention having been explained, a more detailed description of the sequence of operation during the setting up of a connection will now be given with reference to Figs. 26.

The tandem operator is informed of the required number, over an order wire which is not shown, and'she thereupon assigns an idle junction line, for instance, that com 'irising conductors 1 and 2. At the same time that she gives the number of this line to the A operator in the manual exchange, she presses the assignment key 3, whereby the following C11- cuit is completed for the assi nment relay 1: earth, armature 16 and its back contact, operated springs of assignment key 3, armature 52 and its back contact, normally closed springscontrolled by armature 7, winding of relay 4 to battery. Relay 4, upon operating at armature 5 prepares a circuit for the trunk busylamp 65, at armature 6 removes earth from test contact 66 in the bank of the trunk finder, and prepares a circuit for relay 10, at armature 7 completes a locking circuit for itself so that the operator need not keep the assignment key pressed, at armature 8 opens a point in the circuit of relay 37, and at armature 9 completes a starting circuit which extends as follows: earth, front contact and armature 9, lead 19, wiper 105 of the outlet finder, lead 20, winding of relay 21 to battery. Relay 21 thereupon operates, at armature 23 connects switching relay 25 to earth at arma ture 29 in series with rotary magnet 26, and at armature 22 connects test wiper 68 to the junction of relay 25 and magnet 26. Relay 21 also at armature 24: opens a point in the circuit of relay 30. The trunk finder is thus started up and commences to hunt for the contact 66 from which the earth has been removed by the operation of the corresponding assignment relay 4.

A circuit is also completed from armature 9 over wiper 105, back contact and armature 122, winding of relay 107 to battery. Relay 107 at its armature 108 lights the outlet guard lamp 130 and prepares a locking circuit over the normally closed springs 137 of the outlet disconnect key for relay 25, at armature 109 prepares a circuit from earth at armature 150 for relay 111, and at armature 110 connects rotary magnet 126 to wiper 127 in the bank of the sender selector so that if this wiper is on an earthed contact the switch commences to hunt for an idle impulse sender. When this is found, relay 111 is no longer short circuited and operates, thereupon at its armature 112 completing a circuit for relay 117, and at its armature 113 completing an alternative circuit for relay 25 so that this shall not be deenergized when relay 107 releases. Moreover at its armature 114; it shunts armature 109 so as to complete a locking circuit for itself, at armature 115 opens the circuit of rotary magnet- 126 and places earth on test wiper 127, and at armature 116 opens a point in the circuit through the lower winding of relay 128. hen earth is connected to lead 135 over wiper 127, the holding relay 253 is energized and at its armatures 258, 259 and 260 opens points in the circuit of ture 28 it also completes a locking circuit for itself and at armature 29 prepares a circuit for relay 30. The effect of the connection of earth to contact 66 is to complete a circuit which extends from contact 66, armature 6 and its front contact, back contact and armature 40, normally closed springs 69 of the busy and cancel key, winding of relay 10 to battery. Relay 10 upon operating, at armatures 11 and 18 connects the outgoing trunk conductors 34: and by way of contacts 71 and 72, wipers 73 and 7 1 to leads 75 and 76, at armature 12 completes a circuit for the trunk lamp which thereupon flickers under the control of the flicker drum 77, at armature 13 removes earth from back contact of armature 6 so that this shall not be connected to contact 66 when relay 1 deenergizes, at armature 1 1 completes a locking circuit for itself, at armature 15 opens the circuit for relay 4,

at armature 16 opens another point in the circuit of relay {1 and completes a circuit for the upper winding of busy relay 59, and at armature 17 prepares a circuit for relay 37. When relay 21 deenergizes'on the removal of earth from lead 19 armature'24 engages its back contact and a circuit is completed for the upper winding of relay 30. This relay then operates its light armature 31' whereby earth is connected to the lower winding which is thus short circuited. The purpose of this relay is to initiate the sending of impulses if this has not started when the operator presses a new assignment key as will be fully explained subsequently.

Relay 117 of the outlet relay group operates when its circuit is completed, at its armatures 118, 119, 120 and 121 connects the leads from the banks of the outlet finder through to the sender selector, at its armature 122 opens the circuit of relay 107 whereupon this relay deenergizes, at armature 123 prepares the circuit of relay 151, at armature 12 1 prepares the circuit of relay Y157 and at armature 125 completes another circuit 7 for causing the trunk lamp 65 to flicker. Thus relays 111 and 117 ofthe outlet relay group, relay 25 of the trunk finder and relays 10 and 59 in the trunk relay group are now operated. This is on the assumption, which has been made in order to simplify the description, that the A operator has not yet plugged in. The operation of relay 59 is without function at this stage since armature 16 is operated. The Operator may now proceed to set up the required number on her digit keys. I

For the sake of example suppose in the first instance that the wanted party is an automatic subscriber and that his number is 9013456; of this the first three digits 901 will be used for exchange selecting purposes, and it will be assumed that they are converted into the digits 40. When the digit key 9 is pressed, acircuit is completed from earth, operated spring of digit key 9, lead 163,

wiper 103, front contact and armature 120, back contact and armature 148, wiper 143, lead 133, armature 209 and its back contact, wiper 203, lead 214, lower winding of relay 301, lead 302, back contact and armature 215, winding of relay 216 to battery. Relays 301 and 216 energize in series in this circuit, and the former at its upper armature locks itself up over its upper winding to lead 303 which extends by way of armature 217 and its back contact, normally closed spring 218 of the sender disconnect key to lead 135 and thence over wiper 127, back contact and armature158 to earth on the front contact of armature 115. Relay 216 upon operating, at armature 219 completes a circuit for rotary magnet 221 of the input control switch which is arranged to step on release, and at armature 220 completes a circuit for slow relay 222 which thereupon operates its armatures and 224 for a purpose which will bedescribed subsequently.

4. circuit is also completed from the operated springs of digit key 9 over lead 164 for relay 165,-which energizes and at its arma-' ture 166 completes the following circuit: earth, front contact and armature 1.66, wiper 104, front contact and armature 121, back contact and armature 1.52, lead 85, armature 33 and its back contact,'lead 86, wiper 144, lead 134, armature and its back contact, armature 210 and its bacli contact, ar-

natnre 226 audits back contact, viper 204,

lead 227, lower winding of relay 305 to lead 302 and thence through the winding of relay 216 as before. Relay 305 energi/l-es and locks up to lead 303 as did relay 301 and also operates its lower armatures. When the operator releases the digitkey 9, relay 216 is deenergized and opens the circuit of magnet 221 so that the wipers of the input control switch are moved on one step in readiness for recording the second digit. 7

V The operator will now press the digit key 0, whereupon at one of the operated springs of thiskey. a circuit will be complete over lead 163, which will be similar to that just described except that it will now extend over wiper 204 in its second position to the third relay 306 in the second storage group. The operation of the digit key 0 also completes a circuit over lead 162, wiper 102, front contact and armature 119, back contact and armature 147, wiper 142, lead 132, armature 208 and its backcontact, wiper 202 and from the second contact in its bank to relay 307. Relays 306 and 307 energize in series With relay 216 as previously described and lock themselves up to lead 303. Relay 216 remains energized until the key is released,

whereupon the wipers of the input control switch are advanced into their third position.

The neXt digit on the assumption made is 1 and when the corresponding digit key is pressed a circuit is completed from earth, operated springs of key 1, lead 161, wiper 101, armature 118 and its front contact,

wiper 141, lead 131, armature 207 and its ture 115, at armature 234 prepares a circuit for relay 238, at armature 237 prepares a circuit over lead 253 for relay 404 and at armatures 235 and 236 completes a circuit over lead 241, armature 401 and its back contact, armature 410 and its back contact, lead 369, back contact. and armature 320, winding of rotary magnet 315 to battery, and in parallel thereto through the rotary magnets of the other code switches, if there are more than one. These switches are thus set in operation and continue to hunt till wipers 334 and 335 engage the contacts 329, 330 and 331 connected to leads 326, 327 and 328 respectively which have been marked by the operation of the first three sets of storage relays in response to the dialling of the digits 901. Relay 316 is of the shunt field type and only operates its a-rmatures when it isenergized by current through both its windings in the proper direction; in the case shown, this condition is only fulfilled when wiper 334 finds battery and'wipers 333 and 335 at the same time find earth. There is thus no danger of relay 316 being energized when the associated wipers engage contacts which have been marked in response to some other code very similar to the one in question, for instance having two digits the same. In the present case since relays 301 and 305 are operated, earth is connected to contact 329 over armature 322 and its back contact, armature and its back contact, armature 324 and its front contact, and armature325 and its front contact. switches are hunting the operator will set While the code up the remaining digits 3456, whereupon relays 309 and 310 in the fourth storage group, 311 in the fifth, 312 in the sixtln and 313 and 314 in the seventh storage group are energized, and lock up to the holding earth in the manner previously described. Vhen the proper code switch i. e., the one shown, comes to rest having found the marked contacts, shunt lield relay 316 is operated and at its armatures 317, 318 and 319 connects up its wipers 336, 337 and 338 to the controlling leads 339, 340 and 341, respectively, at ar mature 320 opens the circuit of rotary magnet 315, and at armature 321 completes a circuit for relay 400. Relay 400 upon encrgizing, at its armature 401 opens the circuit of all the rotary magnets, at its armature 403 prepares a circuit for the stepping impulse sender and at its armature 402 opens the circuit of relay 404, the use and purpose of which will be described later.

After the setting up of the seventh and last digit, the input control switch will he stepped on in the usual manner, so that it will be moved to its eighth position. Under these circumstances, While relay 222 holds up, a circuit is completed as follows: earth, wiper 206, contact 344, armature 223, and its back contact, back contact and armature 225, lead 134, wiper 144, lead 86, back contact and armature 33, lead 85, armature-152 and its back contact, armature 121 and its front contact, wiper 104, armature 166 and its back contact, winding of relay 167 to battery. Relay 167 upon operating, at its armature 168 completes a circuit which may extend to a totalling meter for registering the total number of calls dealt with by the position, at armature 169 completes a circuit for rotary magnet 160, whereupon the wipers of the outlet finder are moved on one step and at armature 173 completes a circuit which extends over front con tact and armature 123, winding of relay 151 to battery. At armatures 170, 171, and 172 similar circuits are prepared for relays similar to 151 associated with the other outlets, but as only one outlet at a time will be in a condition to have a starting circuit completed, the operation of these armatures is in this case without effect. Relay 151 upon operating at armature 153 connects lead 79 directly to test wiper 127, at armature 154 prepares a circuit for relay 145, at armature 155 completes a locking circuit for itself, at armature 156 opens a point in the circuit of relay 157, and at armature 174 opens a point in the circuit for causing the trunk lamp to flicker.

he further operation is now dependent upon whether the A operator at the originating manual exchange has plugged into the trunk assigned to her; in the normal course this will already have happened so that the sending of impulses will now at once commence. If she has not done so, impulse sending will be held up until she does; thereupon battery is connected to the lower truck conductor 2 at the distant end and a circuit then extends over conductor 2, normally closed springs 80, winding of relay 53, normally closed springs 67 of the busy or cancel key to earth. Relay 53 thereupon operates, at its armatures 54 and 55 alters the circuit of the trunk busy lamp 65, at armature 56 prepares a circuit for the lower winding of relay 59 and at armature 57 completes a circuit for the polarizing winding of relay 50 and also a circuit for relay 37 which extends over armature 17 and its front contact, back contact and armature 8, winding of relay 37 to battery. Uponthe operation of relay 37, at armature 38 earth is fed forward over the'release trunk conductor 36 to the succeeding selector. At armature 39 a circuit is completed for causing the trunk busy lamp 65 to glow continuously, at armature 40 the initial energizing circuit of relay 10 is opened and at armature 41 the circuit over the upper winding of relay 59 is opened. Relay 37 furthermore at armature 42 completes a lockingcircuit for itself, at

armature 43 prepares a circuit for the outlet cancel relay 62, at armature 44 completes a circuit for starting the sending of impulses and at armature 45 connects relay 46 and the upper winding of relay 50 across the outgoing trunk line so as to prepare the supervisory circuit.

The circuit'completed by the operation of armature 44 extends over contact 87, wiper 88, lead 84, normally closed springs 138 of the outlet disconnect key, armature 154 and its front contact, winding of relay 145 to battery. Relay 145 upon energizing, at armature 150 opens the circuit of relay 111 and at armature 149 connects the earth on lead 84 by way of wiper 146, lead 136, armature 247 and its back contact to relay 213 which thereupon operates. At arinatures 207, 208, 209 and 210 the circuits to the wipers 201, 202, 203 and 204 are opened and at the front con tacts of armatures 208 and 209, the impulsing leads 249 and 250 are connected through to leads 132 and 133. At armature 211 earth is connected to lead 135 to replace that removed at armature 115 when relay 111 deenergizes, but as relay 111 is made slow to release there is no discontinuity in this opera tion. Relay 213 furthermore at armature 212 completes a circuit for relay 230 which by operating its armature 215 opens the energizing circuit of the storage relays,- while at armature 252a circuit is completed from earth at the front contact of armature 403, armature- 407 and its back cont-act, interrupter springs 420, which are driven so as to be opened about ten times per second, lead 270, armature 252 and its front contact, lead 271, back contact and armature 445, winding of rotary magnet 431 to battery.

Upon the first completion of this circuit when springs 420 close magnet 431 is energized and operates its interrupter springs 436 and 437 neither of which however perform any useful function in this instance. hen springs 420 next open, magnet 431 releases and advances wipers 432 and 433 one step. A circuit is now completed from the earthed second contact in the bank of wiper 433 for relay 439 which operates and at its armature 440 prepares a locking circuit for relay 441 and at armature 438 removes a shunt from across the impulsing leads 249 and 250 leaving them under the sole control of armature 437. hen therefore magnet 431 next energizes, an interruption is produced in the loop across the outgoing trunk leads which extends as follows lead 34, working contact and armature 11, contact 71, wiper 73, lead 75, front contact and armature 147, wiper 142, lead 132, armature 208 and its front contact, lead 249, normally closed springs controlled by armature 467, armature 437 and its back contact, normally closed springs controlled by armature 468, lead 250, front contact and armature 209, lead 133, wiper 143, arn'iature 148,

and its front contact, lead 76, wiper 74, contact 72, armature 18 and its front contact to lead 35. Upon the next 01 ening of springs 420, magnet 431 deenergizes and advances wipers 432 and 433 another step. This operation continues until the wiper 432 oncounters a contact to which earth is connected. As mentioned above, it will be assumed that in the present case the code 901 set up by the calling operator is converted into the code 40 by suitable cross connections at the intermediate distributing frame (hereafter referred to as the I. D. In consequence, earth is connected to the sixth contact in the bank of wiper 432 over the following circuit earth, wiper 451 of the output control switch, and the first contact in its bank, armature 413 and its back contact, lead 341, armature 319 and its front contact, wiper 338, contact 344, terminal 345 on the left hand side of the I. D. F, jumper to terminal 346 on the right hand side ofthe l. D. 1 lead 370 to contact 447; hence when the wiper arrives on this contact 447, a circuit is completed for relay 441. At armature 442 it completes a locking circuit for itself, at armature 443 completes a circuit for automatically advancing the wipers 432 and 433 to their normal position, at armature 444 completes a circuit for the magnet 443 of the output control switch. at armature 445 opens the circuit from the impulse springs 420 and at armature 445 shunts the interrupter springs 437 so that the subsequent operations of magnet 431 are ineffective to send impulses over the outgoing trunk line. It will be appreciated that four impulses will have been sent to the distant selector when springs 437 are thus shunted wipers 432 and 433 are now automatically stepped on under the control of interrupter contact 436 until viper reaches the dead contact 449 Whereupon the circuit of relay 439 is opened and it deenergizes slowly, thereupon at its armature 440 opening the circuit of relay 441 which also deenergizes slowly. When armature 444 leaves its front contact, the circuit of magnet 448 is opened and it operates to advance the Wipers 451, 452, 453 and 454 one step into engagement with the second contacts in their banks. Earth is now connected over wiper 451, armature 411 and its back contact, lead 340, armature 318 and its front contact, wiper 337, Contact 343, terminal 347 on the left hand side of the I. D. F. terminal 348 on the right hand side of the I. D. 1W, lead 350 to contact 450. When the circuit of the rotary magnet 431 is again completed by the engagement of armature 445 and its back contact, wipers 432 and 433 are again stepped around in the manner previously described, and after they have moved one step relay 439 is energized,and, by operating armature 438, places the outgoing trunk conductors under the sole control of armature 437. It will be apparent in this case that ten impulses will be sent out before W116i 432 engages with contact 450. iVheu this occurs relay 441 will he energized before and wipers 432 and 433 will be automatically returned to their home position whereupon the circuit of relay 439 will be opened.

As in this instance it is being assumed that the call is going to another automatic exchange, the second sender for sending the code impulses will. not in this case be required and the numerical digits will be sent out by the stepping impulse sender, which must thus continue to operate. Vhen relay 441 deenergizes again, the circuit of magnet 448 is opened and wipers 451, 452,. 453, 454, of the output control switch are moved on. a further step. Since, however, it is desired to convert the code 901 comprising three digits into the code 40 comprising only two, it is now necessary that the output control switch should he stepped on past position 3 corresponding to a third exchange selecting digit. This is effected over wiper 336 of the code switch, since a circuit may be traced from earth, wiper 45 1, third contact in its bank, armature 411 and its back contact, lead 339, armature 317 and its front contact, wiper 336, contact 342, cross connection to terminal 351 on the right hand side of the I. D. F, lead 352 to the. third contact in the bank of wiper 453, so that the rotary magnet 448 receives an impulse and the wipers of the output control switch are moved into the position 4. In this case contact 456 in the bank of wiper 453 are all connected to earth as shown, consequently the output control switch will he stepped on to its position 8. These extra contacts are provided to permit the sending of more than three code digits should it be necessary as fully described in the application Serial No. 723,124, previously referred to.

The output control switch is now in condition to control the sending of the numericaldigits, which takes place in a manner very similar to that which has been already described tor the. code digits except that obviously in this case the contact marked in the bank of wiper corresponds to the number set up by the tandem operator. Thus the operation oi. relays 309 and 310 will have the eiiect of connecting earth to lead 353 which is connect-ed to the contact in the bank of wiper 432 corresponding to a train of three impulses. When these three impulses have been sent relay 441 is energized, the transmission of impulses ceases and the impulse control switch is stepped on into its home position whereupon relays 439 and 441 deenergize. The output control switch is then moved on so as to control the. sending 01" the next digit which it has been assumed is 4 and accordingly the contact corresponding to a train of four impulses is marked in the bank of wiper 432 by the operation of relay 311. \Vhen this has been completed, the remaining digits 5 and 6 are sent in a similar manner and when relay 441 deenergizes after the sending of the last digit the wipers of the output control switch are moved on into their eleventh position. 7

In this position a circuit is completed from earth on the eleventh contact in the bank of wiper 454 and said wiper, lead 455, lower winding of relay 246 to battery. Relay 246 thereupon operates, at its armature 248 closes another point in the busy chain circuit so that the circuit is not opened when armature 261 falls away, at armature 247 opens the circuit of relay 213, at armature 217 removes earth from lead 135 and at armature 225 opens the circuit over lead 134 so as to prevent any further earth connections to this lead. Re-

I lay 213 is deenergized upon the operation of armature 247 and at armature 211 removes earth from lead 303 so that all the operated storage relays are released and also relay 253, while at armature 212 relay 213 opens the circuit of relay 230. The release of the storage relays opens the circuit of the operated shunt field relay which accordingly deenergizes and opens the circuit of relay 400 which also deenergizes. The opening of contact 252 on the deenergization of relay 230 prevents the impulse control switch from operating further, but in case it should be off normal at this time it is returned to its normal position over a circuit including armature 251 and its back contact. The code switches remain in the position last used. so that no circuit is necessary for returning them to normal. The deenergization of relay 253 completes a circuit at armature 255 for magnet 221 including its interrupter contact so that the input control switch is automatically moved on into one of its normal positions, of which three may conveniently be provided as shown it the switehis an ordinary point rotary line switch. At armature 254 a circuit is completed over the multipled contacts in the bank of wiper 452 and said wiper for magnet 448 so that the output control switch is restored to normal. Over armatures 258, 259 and 260 additional circuits are completed for relay 246 so as to maintain this relay operated until all the switches have been returned to their normal positions; this obviates the possibility of the impulse sender being taken into use for another call before it is ready. The removal of earth from lead 135 results in the deenergization of relay 151 which by releasing its armature 154 effects the deenergiza-tion of relay 145. Furthermore the removal of earth from lead 135 and hence from lead 83 opens the locking circuit of relay 10 which accordingly deenergizes and at the normally closed springs controlled by armatures 11 and 18 connects the outgoing trunk conductors 34 and 35 through. [it armature 16 earth is momentarily connected to conductor 1 to inform the A operator that sending has ceased andat armature 13 earth is replaced on the contact "66 so as to guard the trunk line against being taken into use by another finder. When relay 151 deenergizes, armature 153 leaves its front contact and earth is thereupon removed from lead 79, in consequence of which switching relay 25 in the trunk finder is deenergized and the trunk finder is thus restored to normal since its wipers remain on the contacts last used. It will be noted that earth is only removed momentarily from lead 135,'being replaced at the front contact of armature 217 when relay 253 deenergizes, so that the impulse sender is guarded against seizure until relay 246 releases. All the apparatus connected with the particular outlet and impulse sender used has now been released and the impulse sender may be seized by another operator. When relay 1O deenergizes, a circuit is completed over the loop for relays 46 and 50 only the former of which however now operates.

Since it has been assumed that the call has gone over automatic switches to the wanted subscriber, he will be rung in the usual manner by the operation of the connector and when he replies the current flow over the speaking leads 34 and 35.will be reversed. This current will then be in a direction to operate relay 50, which at its armature 51 connects the retardation coil 58 to conductor 1, thereby giving the calling operator answering smaervision and at its armature 52 opens a point in the circuit of the assignment relay co that no damage will be done should the AS1101 press the assignment key 3 by misl take while the connection remains set up.

Upon the termination of the conversation when the called party hangs up relay 50 will again deenergize and by disconnecting the retardation coil 58 will notify the calling operator that she may take down the conn ction. lVhen she removes the plug, relay 53 will deenergize, thereby opening the circuit of relay 37, which at armature 39, extinguishes the trunk busy lamp 65. All the apparatus associated with the particular trunk line is thus restored to normal and the trunk line may be used for setting up a further connection.

The case will now be considered in which a call instead of being extended entirely over automatic switches to the wanted party is made to a call indicator exchange, in which event after the exchange selecting operation effected in response to the first three digits set up by the tandem operator, the numerical digits of the wanted partys number are sent over the trunk line to the manual exchange in code. The code employed in this instance is that described in copending application of Ostline, Ser. No. 747 ,373, filed N 0v. 1, 1924 and the apparatus for responding to it may be 01"? the type there shown.

In order to explain clearly the functions of the various pieces of apparatus, it will be assumed that the manual exchange is represented by the code 475 as set up by the tandem operator and that this is then converted by means of the code switches into the two digit code 85. The subscribers number may for convenience be assumed to be 3456 as before and in this case this number is sent out by means of code impulses as about to be de scribed. It will further be assumed that the manual exchange is comparatively near so that the trunk line from the tandem exchange to it will be short. Under these circumstances it is desirable to insert certain re. tances in the circuit over which the code impulses are sent in order to bring the total resistances of the circuit approximately up to that of the long st trunk line to a call indicator exchange w rich may be reached from the tandem exchange; thus a standard adjustment may be employed for the responding relays which is equally suitable for calls from all exchanges.

The ellect of the setting up of the number 4753456 will be readily understood from the preceding description and need not be considered in detail. Suppose that the contacts marked in accordance with the exchange code are the contacts 354, 355 and 356. Then when the code switch comes to rest, contacts 357, 358, and 359 will be connected up over the wipers 336, 337 and 338, and contact 359 will control the sending of eight stepping impulses and contact 358 the sending of five. YVhen however, the output control switch is moved to its third position, a circuit is completed over contact 357, terminal 360 and terminal 361 on the I.D.F., lead 362, upper winding of relay 459, upper winding of relay 456 to battery. Relays 456 and 459 both. operate in this circuit and at their armatures 458 and 461 remove the shunts around the resistances 462 and 463, respectively, and at their armatures 457 and 460 complete a circuit which extends over back contact and armature 465, upper winding of relay 470 to battery. Relay 470 thereupon operates, at its armatures 471 and 472 prepares a locking circuit for its lower winding over the outgoing trunk leads, at armature 473 completes a circuitl'or relay 464 and at armature 474 opens the starting cir- Clllb for the code sending switch. Relay 464 at once energizes, at armature 465 opens the initial energizing circuit of relay 470, at armature 466 completes a locking circuit for itself to earth on lead 254 and at armatures 467 and 468 disconnects the leads from the stepping impulse control switch and connects the impulsing leads 249 and 250 through to the wipers 47 5 and 47 6. Relay 470 is held up over the trunk line as described in the application of Ostline, Serial H0. 747, 373, liled Nov. 1, 1924, until the operator at the distant manual exchange is ready to deal with the call, whereupon the loop is broken and relay 470 deenergizes.

A circuit is thereupon completed from earth on lead 254, armature 47 9 and its back contact, front contact and armature 469, arn'iature 474 and its back contact, first contact in the bank of" wiper 477 and said wiper, armature 482 and its back contact, winding of driving magnet 483 to battery. At this point it may be desirable to explain the inter-operation of relay 48). and driving magnet 483. t will be seen from the drawings that relay 481 is normally short-circuited by interrupter contact 484 and that the circuit ot the driving magnet 483 is completed over armature 482 and its back contact, the sequence of operations being that when the magnet is energized it opens the contact 484, thereby permitting relay 481 to energize so that armature 482 leaves its back contact. The circuit of the driving magnet being thus opened it releases and again closes the interrupter contact 484. The particular advantage of this arrangement is that in a case such as the present where the speed of rotation is of importance the armature 482 may be adjusted so that the rate of generation of impulses is as high as is consistent with the reliable operation of the responding apparatus at the call indicator ex change; then in course of time, when wear of the contacts has taken place, the tendency will be for impulses to be generated at a slower rate and in no case at a quicker rate. There is thus no danger that after the lapse of time the speed of generation of impulses will be increased so that the call indicator equipment does not operate properly. An

advantageous arrangement is to have micrometer ad ustment on armature 482 as indicated by means of which the required speed of generation in ay be determined withcircuit is completed as follows: earth, con tact 485, wiper 475, resistance 463, resistance 462, armature 467 and its front contact, lead 249, front contact and armature 208, lead 132,

wiper 142, armature 147 and its front contact, lead 7 5, wiper 73, contact 71, armature 11 and its front contact, outgoing trunk conductor 34, over the responding apparatus in thecall indicator exchange, trunk conductor 35, front contact and armature 18, contact 72, wiper I 74, conductor 76, front contactand armatur 148, wiper 143, lead 133, armature 209 and its front contact, lead 250, front contact and armature 468, wiper 476, contact 486, lead 487, front contact and armature 363, high resistance 364 to battery; this constitutes what may be termed a'light positive, impulses lVhen wipers 475, 476 and 477 come into engagement with the nextset of contacts, ac1rcuit is completed from'earth in the bank of sent.

wiper 47 6 and said wiper, over the previously described circuit in the IBVGL'SB'dll'QOtlOIl, to

wiper 475, contact 488, lead489, armature 365 and its front contact,.back contact and armature 366, low resistance'367 to battery. Since the low resistance 367 has been inserted in this circuit rather than the high resistance 364, this will beaheavy impulse and as the current is in the reverse direction to that tak-i ingplace previously, is a negative impulse.

in the next position of the code sending switch 110 circuit is COlilPlOtCtl SlIiCe owing to the operation of relay 310 in'the fourthstor group, armature 368 has left itsbaclrcoii- I tact. In the following position ofthe switch current flows in accircuit'whi'ch is identical with that last described except that it ncludes V the high resistance 364 HiStOtI-(lOf the low esistance367 so that a light negative impulse is four positions correspond As soon as the digit have been ing to the-first numerical passed over, the transmission of the second digit commences forthwitln The contacts controlling the code sendingswitch on the fifth storage relay group have not been shown,

but are exactly similar to thosevsl own. on the nth groups id ,1 sequence he roller cct ci'fil ner; When they reach the third set of contacts 'matic culty. It may be said that-in the first posi '1 tion of the switch no impulseat all is sent, in

thesecond position a light negative impulse, v

in the third position a positive impulse and in the fourth position afurther light negative impulse. Similarly the third and fourth" Y numerical digits are sent, the third digit con sisting of two l ght negative, impulses and" the fourth digit consisting of a positive iin pulse, a light negative impulseand a heavy 1 negative impulse. When all the digitshave been transmitted, the number is decoded and displayed to the manual operator who will complete the connection in any suitable man- ;As the code sending switch continues to move forward, when wiper477 engages its 19th eontact,'tlie rotary magiiet 483 is energized in series with. the relay 478 which. is of such low. resistanceas to permit the magnet ft-ogoperate; ,Relay 478 also energizes and 'at its armature 479 opens the int-ial energ zing circuit for starting up the code send ng switch so that this will bebrought to rest j when it reaches itsfirst'contact, and at armature 480 completes a circuitover lead 455 for relay 246 which operates with the results previously described. All the apparatus in the )revious case and the o aerations in'tl etrunk relay group are similar, suitable arra gezments being provided atthe call indicator ex: change for lIlStiTtIiCG forcur-rent reversal so asv to give supervisionyto the operator at the originating manual exchange.

call indicator exchangewere reached over a truiilcline which had a greater resistance, the connection at the'llD. F. would bealtered so that only one or possibly neither of the compensatingrelays 456' and 459 were operated; for this purpose terminal360 would be cross" connected to one of terminals-371, 372 or 373.

'The case in which terminal 373 :was used would clearly be where the resistance the. trunk lineabove tllttt;0fthe trunk line coii-" sideiied in the first case'was equal to the sum if resistances 462 and 463. 1 In case the manual exchange were reached inresponse to the three digit code, it would be necessary to have a special code relay for energizing relay 470 or alternatively an additionalawiper mightbe provided on the code switches, though this would probably ,beundersirable. a The mode of operation of suclrajcode relay and the necessary connections to the banks, of the sender is then released asdescribed inthe y e no, It should. be understood that, in case-tho wipers of the output control switch are fully 1 V shown-in the application Serial No. 523,124,

previously referred to. v 1 Obviously an y, of the cases provided forth ere 56311 be dealt with on similar lines in, the present instance. e .Clhe arrangements for .secuiinggthe autoarting tor does not set iliflilflfiilc l full t up the Cit? the sending of impulses in ice ' for instance that she sets up only three digits such as maybe required for reaching a com plalnt or lnformation operators positlon; in

this case relay 2 38 comes into operation The interrupter 245 isdriven at such a speed that its'upplies an earthed impulseat intervals preferably once every four seconds. When relay 232 is operatedafterithree digits have whichis of thetwo step type operates its iight armature 239 whereby earth from lead135is connected to the other terminal'of its'upper been set up, interrupter 245is connected up over armature 240 and is back contact, front contact and armature 234,- back contact and armature 224, lower winding of relay 238 to battery. When earth comes on, relay 238 winding. On the termination'of the impulse,

. operator is still setting up an ordinary seven relay 238 energizes fully over both' its windings in seriesIand at armature 240 transfers the connection fromthe interrupter to lead 134 by way: of the back contact and armature 225. It will. be noted that this circuit for relay 238' is not operative as long as relay 222 is energized-owing to the operation of armature 224. This will occur while the number 'is being set up and for a short time afterwards, and serves to prevent the initiatlon of the sending of lmpulses while the digit number." It will be noted also that relay 238 operates armature 226 so that the i connection of earth to the lead 134 shall not op'erateone of the storage relays in formstance the. fourth group. The connection of earth to lead 134 when interrupter 245 again closes its contacts operates the start relay 167 in the manner previously-described and the sending of the stored digits takes place as before. A further means for automatically ciated withthe" new trunk line will be to its lower winding.

operate the line relay 21 of the same trunk finder as is already in use, and this will accordingly operate its armatures, of which however, only the armature 24 1s able to produce any effect. 1 Relay 30 it will be remembered has operated its light armature 31 so. that earth is connected to both terminals of When armature 24 leaves its back contact, however, earth is rep moved, from the mid'dleipoint of the windto ing of relay 30 and'this'relay then operates fully, thereby at armature 33 and its front contact connecting earth to lead and hence over wiper 104 and armature 166 and its back contact to the start relay 167, so that the starting of the sending takes place as before.

The operation of relay 167 completes a tin cuit' for the rotary magnet .160 so that the outlet finder is moved on one step and another trunk finder is taken intouse over which the'call may be set up in the ordinary manner.

The case will now be considered in which owing to a mistake on the part of the tandem operator an exchange code is set up which does not correspond to any of those provided for. In this event if no arrangements were made,'the code switches would continue to hunt and if the operator remained unaware of her mistake, the call'would be lost or mutilated. "To guard againstthis, relays 405 and 408 are provided and the operation'is as followsi The interrupter 242 in Fig. 4 is ar- P ranged to send an earth impulse at intervals of preferably two seconds; hence when relay 232 is energized on the input control switch arriving at its fourth position, a circuit is prepared-from earth over interrupter242, front contact and armature 237, lead 253, armature 406 and its back contact, back con tact and armature 402, upper winding of re- Y lay 404 to battery. This circuit it'should'be understood is completed in any case in the normal working but when a code switch finds the marked contacts relay 400 is operated and at armature'402 the circuit of relay 404 is opened. .In case a deadnumberihas been set 4 up,"however, upon the first impulse given by the interrupter 242, relay 404 will'be partially energized over its upper winding and will operate its 1 light armature 40 5 whereupon earth from lead 254will be connected to the other terminal of its lowerwinding; On the termination ofthe impulse, the lower .winding will no longer be short-circuited and the relay will operate fully, thereupon at its armature'40 6 transferring the circuit over lead 253 to the winding of relay 408." Consequently after another two seconds, when earth is again connected to lead 253, relay 408 isenergized. At armature 414i't locks itself to lead 254, at armature 409 completes a circuit for relay400, at armature 410 opens .the circuits for the rotary magnets of the code switches so that these are brought to rest and at armatures 411, 412, and 413 disconnects .theleads from the bank of Wiper 451 from the leads 339, 340'and 341" and connects them through to special terminals 374, 375, and 376 on the I. D. F., which are suitably cross connected so as to route the call to a special operators position. 'Thisispecial operator then deals withthe call and is able to inform the calling party as to why this-call has 7 failed. After theimpulses have been sent out for routingthe call to the operator,'relay 246 is operated, for instance by a special 'earth connection to the eighth contact'in the bank of wiper 454, and the impulse sender and the associated apparatus are releasedin the man ner previously described.

7 The purpose of relay 264 may now be ex- 1 x and its back contact.

the interrupter 257 next gives an impulse re-- plained. The interrupter 257 is arranged to give an earth impulse conveniently once every eight seconds and when relay 253 operates on the seizure of the impulse sender, interrupter 257 is connected up over armature 266 Consequently when lay 26 i is partially energized by its lower winding and operates its light armature 265 and on the termination of the impulses operates fully, thereupon at its armature 266 con- I necting theinterrupter257 to lead 155. After a further eight seconds therefore, in case the mpulse sender 18 still 1n use, relay 26& will be' energized frominterrupter 257 and will operate as usual to release all the apparatus. It is thus impossible for-an impulse sender to rcmaiirloclred up indefinitely owingto some defect. The time allowed, from eight to sixteen seconds is arranged to be amply sufficient for the complete operation of the impulse sender in the normalcourse. V

In order that the operator may release the apparatus in case "she finds she has set up the wrong number, cancellation keys are provided. Two cases must be consideredilirstly that in which the operator discovers her mistake before the actual sending of impulses commences and secondly, that in which sends 'ing has already commenced before she real- I izes her error. In the first case, she will press ture 115 is removcdfromthe lead1'85 so that allithe storage relayswhich have been opera'tcd are released as is also relay 253, whereupon the input control switch is returned to normal. It will be noticed however, that no alteration is IlltlClGtO the condition of the trunk relays and consequently the operator may now proceed to setup the correct num- 1 her and the connection will be completed in y 77 is broken.

I the usual manner. Should: impulse sending actually have commenced however before the mistake is realized, .1twill benecessary for the operator to press-the busy or cancel lCQYJ'VlllClI is associated with the trunkline taken into use. \Vhen she does this the holding earthfor the trunk relay is removed at spring 67 and the trunk lamp 65 is lighted.

' llurtherniore at spring 69 the circuit of relay 10 is opened and at springTO a circuit is complcted for the outlet cancel relay 62 which is connnonto all the trunks. This at-its armature 63 completes a circuit over lead 78 whereby the outlet tinder is moved forward into engagen'ient with another outlet while at 'ar 87 removes earth at armature t4: fromthecontrol lead 84-. and hence it is also removed from lead 136 so that relay 213 deenergizes; This accordingly removed the holding .earth'at armatures 211 and 212 and the impulse sender is released. will: now be necessary tor the operator to press the assignmenthey again and the call will then be set up over a fresh outlet and another impulse sender.

The operation of the busy relay 59 may ;now be considered; is energized over its upper winding from armature 16 after relay 10 operates until relayB'Z operatesy its armature 60 it prepares a busying circu t, which is however, without etl ectat this time owi'ngto the removal of earth from the back contact of armature 16 but as explained aboveserves to give the manual operator a 1 momentary signal when the sending of impulses 1s finished. Furthermore at armature 61 a circuit is prepared forthe outlet cancel relay 62; After the sending of impulses has commenced, in case either a group slrould be found busy, in which case the selector will be drivento the eleventh contacto in case the calling subscriber should bebusy, busy tone and busy flash battery will be connected alternately to the lower trunk conductor Consequently when relay -10 deenergizeson the termination .of impulse transmission relay 4-6 is only energized intermittently since no circuitis completed for it when battery is connected to conductor A circuit is completed each time relay 46 deenergizes' for the lower winding of relay 59 over back contact and armature 49 and front contact and armature 56. Relay 59; therefore operates. and

at its armature 60i connectsearth intermittentlyto' the trunk conductor 1 so that the CELllIH operator is notified by the flashing ofv thesupervisorylamp, l y The emergency order wire l'tey 'on'theex trcmc left of Fig; 1 is provided .in order that the 1unct1on line from the manual exchange may in case of necessity be'used as an order '-W11. When it'is'operated, at spr ng .82 a

circuit is completed. for the trunk busying lamp 655- and at springs andBlleads 1 and 2 are disconnected-from the trunk relay group and connected to-flea-ds 89 and '60extei'idi-ng to the-usual order wire keys; The lighting" of lamp65 then indicates to. the tandem operator that the trunkline "18 not available,

and must not be assigned.

In casethe trunk lineis out of order, the

busy or cancel key will be operated and this will'have the cfi ect of lighting lamp 65 and placing the trunk relay group in such a con dition that-it cannot be operated. :The out- -let disconnect lieyis-operatedain case a-parfticular outl'etis out of order.

140 lights the outlet guardlanip" 130 and-at soeiated with the o'utlet'in thebank of wiper 106 so that ,this outiet cannot be taken-into use. Atsprings l37anda188 the connections This at spring I p spring 139 connectsearth to thecontact mature 6 1 theconnection of the'fiicker drum f The deen'ergization, of relay chain fcircuit will be closed.

to leads79 and. 84 are broken so that the relays associated with the outlet are rendered in operative. The sender disconnect key will be operated in case a particular sender is out of order whereupon at spring 218 the through circuit for lockin up-the storage relays is brokenand earth is connected to lead 135 so as to prevent the sender being taken into use while at spring 229 point-is completed in the chain circuit, which will now be described.- Eaoh sender has three contacts in parallel in this chain-circuit, springs 229 of. the sender disconnect key, contacts 248 of therelay 246 and contacts 261 of the relay 253. WVhile the sender in normal use, armature 261' will engage lts front contact and. during the release of the sender arn'iature 248 will be operative; thus as long as the sender is not available for use its corresponding point in the When all the senders inv a group (which in the example showncomprisesi25) are in usea circuit will be completed over lead 159 and at armature 116 and its back contact for the lower WlIlClmg of relay 128 which thereupon operates and at its armature 120 busies the outlet having access to this particular group. The outlet finder is thus stepped on into engage ment with another outlet with which the idle senders areassociatedand no time is wasted withuseless hunting. Relay 128 is also provided with an upper Winding which is connected to the fuse alarm' of the trunk finder associated with this outlet. Consequently if the trunk finder should be put-out of action by the blowing of this fuse the outlet would be automatically busied and the operator would not be held up.

The operation of-the various lamps pro vided will now be' considered. The outlet guard lamp 130is operated as long as an outlet is in use or in case the outlet disconnect key is operated. As has already been pointed out, the trunk lamp 65' will glow steadily in case eitherthe emergency order wire key or the busy or cancel key is operated but in order to keep the operator informed of the progress of -the connection, itis arranged that in addition to glowing steadily it may either flash or flicker. In order that this may be better understood, consider first thattho tandem operator completes all her operations before the'lA operator plugs in. When the assignment key is,

pressed the lamp commences to flicker in the following circuit upon the operation of relay .117; earth, flicker drum 77 backcontact and armature 64, common lead- 87, back contact and armature 17 4, armaturel25 and its front contact, common lead 88, armature audits front contact, back contact and armature 54,

back contact and armature 12, trunk lamp 65 to battery. When both the sender selector and the trunk finder have cometo rest, relay energizes and the circuit is then altered so that it now extends from the flicker drum77, back contact and armature 64, armature audits pleted for causing the lamp to glow steadily.

Since the relay 87 remains energized through out the connection the lamp remains lighted also and when it is finally extinguished, the

tandem operator knows that the trunk line is again idle and may be used fol-setting up another connection. In case. the Aoperator plugs in before the B operator presses her as sign'ment key, relay 53 will be operated and a circuit will now be completed from earth, flashing interrupter 48, back contact and armature 47, frontcontact and armature 54, back contact and armature 12 to lamp 65. lVhcn the assignment key is pressed the lamp is extin uished b the o aeration of armature 12 and then lights and glows steadily owing to the operationof armature 39 byrelay 37.

The purpose and method of operation of the supervisory arrangements for the senders will nowv be described. Itwill be noted that all the rotary magnets in thesendcr are connected to ba ttcry through the winding of relay 490 which is of very low'resistance, probably oulya fraction of an ohm. Consequently when any of these magnets are operated, relay 490 pulls up and at itsarinature 491 completes a circuit for the supervisory lamp 492 which circuit extends over the normally closed con- .tacts controlled by armature 5.00, low resistance winding of relayf493 to earth; Lamp 492 therefore'lightsandrelay'493 pullsup and at its armature 494 completes a circuit for opcrating the slow set-or dash-pot relay 495.

nder normal circumstances vthe'magnets will be energized intermlttently and for so short a time that the relay 495will never be, able to close its contact 496. In case however one of the switches should become stuck and current continue to flow through the corresponding magnet, contact 496; would be closedaftera.

suitable interval and relay 497 would thereupon be-energized. This at armatures 499 and 500-completes an alternative circuit for" the supervisory lamp 492 and at its armature .501'connects up relay 502 to the interrupter 498. lVhen relay 502 energizes under the control of the interrupter,'as happens at'intervals,the circuit of the supervisory lamp is transferred from the low resistance relay 493 torela-y 503, the resistance of which is so high that the lamp does not light in series with it.

cuit is completed for the dash pot relay 49.5,so

.Moreover at-armature 504 an'additional cir-' that this will maintain itsarmature'attracted as long as the abnormal conditions persist. The flashing of the supervisory lamp 492 thus lIlCllCltQS to the attendant that there is'trouble pulse senderand this can then belo'e -Wit-l1 one of the switches in a'particular im-' V ked to. It should he remarked that the relay 4% and the lamp 492 and ofcourse, the contact 262 arev individual to each sender, while the supervi sory relays and the key 367 are common to a group of senders. The operation of the key 267 while lighting the corresponding lamps serves to show which senders are in use though these lamps would be already lighted If any ofthe magnets were energized.

WVliat is claimed is: r 1. In a telephone system, an operator7s key board, register setsbnwhicl'i wanted subscribers numbers are stored directlyby said keyboard and sending devices of two different kinds both associatedwi-th and directly controlled by the register sets,-meaiis being prosubsequently transmits impulses of a different kind corresponding to another portion of the required number. v l r a 2. In a telephone system, a register set on which wanted subscribers complete numbers.

are adapted to be initially set up and send lilgtlGVlCGS of two kinds directly controlled by saiduegister set, that part of the register set which, registersthe exchange designation of the wanted subscriber being adapted to cause the operation of one sending device to control switches for selecting the required exchange and also'to determine whether sub: sequently the first device will continue to op-. eratefor the second device be brought into operation to transmit impulses of a different kind in accordance with the setting ofthe other part of the register set which registers the numerical designation of the wanted subscriber. I I 1 1 3. An impulsesending device comprising register sets on which wanted subscribers numbers are stored, sending devices of two kinds associated with the register sets, one for sending impulses to operate the switches which perform an exchange selection function', the other for sending'impulses for operating callindicators at the exchangeselected, and a translating device consisting ofa hunting switch set in operation after the digits'it is to translate have been. registered to siniultaiieousliy test for and: find all con-' tacts whieh'havebeen marked in response to the 're, "istering of said-digits. 7

4:. Pin impulse sending device as claimed in claim 3 in which ittheshunting switchfail'sto find a set ofma'r'ked cont acts withi-n a predetermined time, itsoperation isstopped and a special relay is operated-to trunk the callto an operator. 1

In a telephone system", impulse sending and registering devices, means for"retrans mittingcalled telephone ni'imbers registered on said register devices, means for automati cally causing such retransmission to auto:

matically start a fter a group of numbers have been registered in all the said register devices,

means automatically-eilective' after an interval ifonly a part of a number has 'beenregistered, an;d othermeans' atctimes effective to start the retransmission in the latter instance before "the predetermined, interval (has elapsed; I Y

'6. In a telephone system, an operators switchboard, "trunks extending fr0m the switchboard terminating in automatic switches havin'gvaccess to a plurality of eX-' changes, digit'registering and sending equipment, an assignment'key at theswitchboard, means responsive to the actuation of sai'di key.

for associating trunk" with said hey set and with saiddigit registering and sending equipment, means responsive to the operation 'of various keys of the key set for causingthe corresponding digits to be, registered and subs sequently retransmitted after an interval,

said' assignmentkey also effective upon its being again operated prior to the expiration. of said interval, for causing the retransmission to sta-rtat once.

7 In a telephone system, A and'zB operators switchboards trunk lines extending to other exchanges, impulse registering and transmitting equipment at the B operator s switchboard, an assignment key, means controlled bythe operation-otsaid key for causing the registering and transmitting equipment to be associzited-"witli its associated. trunk, a supervisory signal at the Bswitchboard, 'means for "intermittently;operating-1 saidsignaluntil the trunk and: sender. are' connected and for operating said signal steadily thereafter, a 7 key set 'by means of which the operator at; the B board may: now cause the registration andtransmission of the called number to ta'ke place,.and imeans' for automatically transmitting an impulse backto' the Aboard-responsive 'to tlie' com:- plete transmission of the called number. in 1 a telephone system, automatic switches, keyboard controlled impulse senders common to a number of'opera'tors, said. impulse senders being adapted for use insetting upi both, connections which are completed to a wanted party by means of said automatic switches "and these which are completedby an' operator'at a call indicator positiong' 'circuit arrangements for starting thetransmission of impulses for establishing the desired connection when the full number of digits have been set up and automatically initiated in caseless than thefull numberare used when tl'ieoperator commences to 7 deal with" the succeeding call. V

j 9;' In a telephone-system, a registerset on which wanted subscribers" vnumbers are adapted-to be set up,'sending devices oftwo kindscontrolledby'tlieregi'ster set, that part being adapted to cause the operation of one sending device to control switches for selecting the required exchange and also to determine whether subsequently the first device will continue to operate or thesecond device be brought into operation to transmit impulses of-a dilierent kind iii-accordance with the setting of the other part of the register set which registers the numerical designation of the wanted subscriber, the said sending device for controllingthe generation of aimlate-have been registered to find contacts which have beenmarked in response to the registering of said digits, said hunting .switch being provided with a plurality of wipers threeofwhich are connected to a shunt field relay which on energization serves to bring the switch to rest while'the remain ing wipers in turn serveto control thegeneration of trains ofimpulses of the same kind but'of different values.

11. In a telephone system, register sets on which wanted subscribers numbers are regis tered, sending devices of two kinds associated with said register sets, one for sending impulses to operatethe switches which perform an" exchange selecting function, the others forsending impulses for operating call indicators at the exchange selected, a translating device consisting ofahuntingswitch set in operationafter the digit it isto translate has been registered to find contacts which have been marked in response to the registration of said digits, and means for stopping said hunting switch and for trunking the call to an. operator should the switch fail to find a set of contacts within a predetermined time.

12. In a telephone system, a register set on which wanted subscribers numbers are adapted to be set up, sending devices of two kinds controlled by the said register set, that part of the register set which registers the 7 exchange designation of the wanted subscriber being adapted to first adjust the circuit over which the impulses are to'be sentso as to maintain the resistance of the circuits substantially constant irrespective of the resistanceof the trunk line leadingto the exchange selected and also to determine whether subsequently the first device will continue to operate or the second device he brought into operation to transmit impulses of the different kind in accordance withthe setting of the part of the registerset which numbers are wanted subscriber. V I 13. In a telephone system, a registerset registers the numerical designation of the on which wanted subscribers numbers are adapted to be set up, sending devices of two kinds controlled by thesaid register set, said of relays, one set for each. digit, certain of the sets of relays being provided with two distinct setsof contacts one contact set adapt-' registering set comprisinga plurality of sets let. In a: telephone system, in which connections are set up over automatic switches with the help of operators by means ofkey board controlled impulse senders common to alarge number of operators, and in which the same impulse'senders are adapted to be usedfor setting up both connections which are completed to the wanted parties by means of iltltOlllLtlOSWitCllQS and those which are completed by an operator at a call indicator position, means for causingthe sending of impulses for establishing the desired connections to be initiated when the full number of digits have been set up, and means for causing the sending of impulses to be automatically initiated when the OPBI'LtOI;COH1-- mences to deal with the succeeding call when 7 less than the full number has been set up.

7 15. In a telephone system in which con nections are set up over automatic switches 1 with the help of operators by means of key board controlled impulse senders common to a large number of operators, and in which, the same impulse senders'are adapted to be used forsetting up both connections which are completed to the'wantedparty by means of automatic switches and those which are completed byan operator at a call indicator position, characterized in this, t-hatmeans is provided whereby the sending of impulses for establishing the desired connection is automaticallyinitiatedafter the lapse of a predetermined time. r

16. In a telephone system, a relay register set on which wanted subscribers numbers are stored, a first sending deviceassociated with said relay register set and controlled thereby to send onekind of impulses which correspond to the digits of a wanted number to perform the exchange and station selection, and a second sending device also associated with and controlled by said relay register set to send impulses of a different kind in a code suitable for'operating call indicators at the exchange selected.

17. In a telephone system containing 1nan-' ual oflices and automatic oflices, automatic switches in the automatic oflices responsive to control of a given character, call indicators in the manual offices responsive to control of a difierent character, register senders in the 

